Electrolytic cell for recovering manganese



' J. H. JAcoBs ETA, ELECTROLYTIG .ICIELL FOR RECOVERING MANGANESE Filed Nov. 16, 1944 Ill irramvsv Patented Dec. 14, 1948 ELECTROLYTIC CELL FUR RECOVERING MANGANESE JamesH. Jacobs, Boulder City-,.Nev., and' Warren H.. Yan-oli, Provo, Utah,V assgnors, by mesne assignments, to Crimora Researchy and yBevel-- opment Corporation, Crimora, Va., a corporation. of Virginiav Application November 16, 1944, Serial No. 563,692

This invention relates to electrolytic cells of the compartment type employed in wnningor recovering manganese or similar` metalsto remove anodic sludge from the cell and tov improve the elciency. More particularly, the invention applies to electrolytic cells of the type wherein the anodes are suspended in aV compartment and separated. from the, cathodes. by porous diaphragms. Among other objects, the inventiony aims tcprovide a cell structure'. in whichl a. single feed line for the electrolyte may be employed in place of separate feedlines for each cathode.

Another aim is. to provide a cell structure in which all ot the'cathodesare suspended ina common catholyteof substantially uniform composition which leads to uniformity of deposition en Still another aim is to provide a the cathodes. cell structure so designed that the volume of catholyte, relative to` that of anolyta. may be: greatlyy increased Without the diiculties caused. by expanding, bags. of diaphragme iii-led: with.

at a much higher current density or capacity' than has heretofore been possible The main idea is to. increase the amount of' manganesewhich may beremoved from agiven amount-of.

the solution passing through. the cell, therebyA eiecting ar corresponding decrease; in thel necessary size and cost of the leaching,v and purifica:- tion plant required.

Other aims and advantages of the invention.

will appear in the accompanying description oan.

illustrative embodiment of apparatusr for prac,-

ticing the method, disclosed in theaccompanying drawing, wherein:

Fig. 1 is a side elevation, of a cell embodying the invention, parts being broken away and other'- parts, including ananode and' its diaphragmcovered frame, being shown in section;

Fig. 2 is ay sectional view taken on the line 2"-'-`2 of Fig. 3, showing the diaphragm-covered* framein top plan;

Fig. 3 is an enlarged face View of the anode diaphragm coveredframe with the anode inserted therein; and

Fig. l is a partial transverse sectional view through the center of the cell showing'an anode diaphragm-covered frame and an anode sus;- pended therein.

Heretofore, incompartment type cells employed for electro-Winning manganese and sim ilar metals, the anodic sludge has been' allowed tofcollect at the bottom of the anode compartm'ent when the cathodes were enclosed Within diaphragm-covered frames or in ther bottoms o-fanode bags when the anodes were completely'enclosed in porous diaphragme. In both cases,- the sludge accumulation has caused considerabley dif.- culty. To ameliorate this diiculty; increasedelectrcde spacing and increased volume of theY anode compartment have heretofore been'.r1'eces' sary. The disadvantages of the-se measures' are obvious. When the anodes are completely en'- closed Within diaphragm bags or covers, the bags will eventually ll up with accumulated sludge and burst. This invention provides a cell structure having means whereby the-anodic sludge iscontinuously removed from the space between the anodes and cathodea, thereby making is. possible to maintain a large volume of. catholyte, relative to the anolyte, without increasing the electrode spacing and the sizeof the cell. Incidentally, this arrangement is such that the. cell: can be operated at a much higher eiciency and the canvas covers or diaphrams enclosing. the anodes will last much longer than the anode bags heretofore employed. l

Referring to the illustrated. embodiment of the cell'structure, there is shown a box-like compartment I, which may be made of wood, or other suitable material which will not be affected by the electrolyte solution. It is shown as carrying. suspended' anodes 2 mounted on transverse` bars 3, contacting bus bars t at their opposite ends, and these anodes are guided into frames 5 also suspended inthe compartment and having canvas diaphragms 6 on opposite sides.- Cathode-plates 'iiaresuspended in the compartment from trans`` verse bars 8 contacting bus bars 9 at their opposite ends. These plates may be carried in suitable frames (not shown) which may be made of phenolic resin or other suitable material. The frames are guided in place by suitable notched spacers l0.

In accordance with this invention, the lower portion of the box or cell compartment is shown as being provided with a false bottom il preferably made of wood and spaced above the bottom of the box to provide a lower sludge chamber. Herein, the false bottom is shown as having a rectangular opening, the width of which is determined by the width of the anode frames, and transverse spacer blocks or wooden strips l2 are arranged below the alternate cathode frames, providing spaces to receive the open bottoms of the anode frames to separate the sludge chamber from the upper main cell compartment. The lower, open ends of the anode frames, covered by the canvas diaphragms, are arranged to discharge directly into the sludge chamber at the bottom of the box or cell.

Purified feed solution is delivered to the catholyte through a single conduit I3, preferably arranged at one end of the compartment, and the anolyte is discharged from the sludge chamber through a discharge pipe I4. In this instance, the discharge pipe is shown as rising to a point above the false bottom and extends outwardly through the end wall of the cell at the desired level of the solution in the cell, so that the anolyte will be discharged by gravity iiow.

An ordinary wood launder (not shown) `is em ployed to convey the spent electrolyte to a storage tank, from which it is adapted to be pumped to the leaching plant for leaching more reduced ore. The accumulated sludge ls discharged periodically through a sludge conduit l5, in the bottom of the sludge chamber. The bottom is provided with a sump portion to facilitate draining all the sludge by gravity flow.

The electrolyte in the cell is preferably cooled in the usual manner, by circulating cold water through suitable coils (not shown) .which are made of lead pipe. The water may be artificially cooled in summer by employing mechanical refrigeration.

In the operation of the electrolytic cell, the anodes have to be removed periodically, say, at intervals of every six or eight weeks so that the plates may be cleaned and the clogged anode diaphragms replaced. Calcium sulphate crystals form on the inside of the anode diaphragms and reduce their porosity to such an extent that the solution will not flow through them. Therefore, it is necessary to replace them when the plates and frames are removed.

The cathodes are preferably, though not necessarily, made of special, stainless steel and the bars are preferably covered with lead; while the anodes are preferably composed oi about 99% lead and 1% silver, drilled with holes so as to eliminate labout 40% of the area. Such anodes produce.Y a minimum amount of sludge of high density.

The cell is operated continuously and the cathodes may be removed at about twenty-four hour intervals and dipped into the usual solution of potassium or sodium dichromate, to prevent oxidation of the manganese and they are then Washed in a spray tank and air-dried. The deposited manganese is stripped from the cathode plates in the usual manner, with the recovery of practically all of themetal.

4 The following is an example of the operation of a cell employing the invention:

99a ma e Amdc 15 X32 x void 28 anodes per cell Type 316 stainless stoel containing 18% Cr, 8% Ni and 2% Mo 27 cathodes per cell Current density, anode 8l to 90 amp. per sri. Et.

Cell voltage 5.0-5.3 volts Mn: 34 to 3B grams per liter Feed solution (NHmSOr: 135 to 140 grams per liter SO2: 0.15 grani per liter Mn: 8 to 10 grams per liter (NHmSOr: 155 grams per liter (calculated from ammonia content) SO2: 0.10 gram per liter Mn: 8 to 10 grams per liter .anolyte (NH4) SO: 135 to 140 grams per liter H2SO4: 43 to 50 grams per liter Diaphragm l8oz. canvas Duration of electrclysis 24 hrs.

Pounds Mn per cathode 10 to l2 Current efliciency to 65 per cent Cathode Catholyte Obviously, the invention is not restricted to the particular embodiment thereof herein described but the cell structure is capable of a wide'variety of changes within the scope of the appended claims.

Having thus described the invention, what is claimed is:

l. An electrolytic cell for recovering manganese, comprising, in combination, a box; a plurality of anode and cathode plates suspended therein with their opposite side edges spaced from the opposite side walls of the box, frames for the anodes carrying solution permeable diaphragms V spaced from opposite sides of and completely surrounding each anode, except at its upper and lower ends and providing individual anolyte compartments having open lower ends, all of the cathode plates being located in a common catholyte compartment; a false bottom in the box having openings into which the lower ends of said anode frames project and providing a sludge chamber into which the anodic sludge discharges freely by gravity ilow; means to supply feed solution to the catholyte compartment; and a discharge conduit connected to the sludge chamber through which spent anolyte is drained as the feed solution is supplied.

2. An electrolytic cell of the character described comprising in combination, a box having a false bottom therein dividing it into an electrolyzing chamber and a sludge chamber; cathodes and anodes suspended in the box and spaced from the sides of the box; solution-permeable diaphragms spaced from the opposite sides of each anode extending rdownwardly to said false bottom and also spaced from the sides of the box, thereby providing individual anode compartments, segregated from a common catholyte compartment; said false bottom being impermeable to the catholyte solution between the anode compartments and having openings communicating directly with each anode compartment to permit anodic sludge to gravitate therethrough into the sludge chamber; means to supply electrolyte to the catholyte compartment; and an outlet conduit connected to the sludge chamber to discharge spent anolyte therefrom as the electrolyte is replenished.

3. An electrolytic cell, as set forth in Claim l, wherein the discharge conduit extends upwardly from the sludge chamber to the level of the anolyte in Athe anolyte compartments; and a drain pipe connected to the bottom of the sludge chamber for periodically discharging the accumu- Number lated sludge therefrom. 1,359,002 JAMES H. JACOBS. 1,732,797 WARREN H. YARROLL. 2,286,148 5 2,320,806 REFERENCES CITED The following references are of record in the me of this patent: Numego UNITED STATES PATENTS 10 5441539 Number Name Date 558,970 Lugo et al Apr. 28, 1896 1,231,955 Slater July 3, 1917 Name Date Thomas Nov. 16, 1920 Eustis Oct. 22, 1929 Mantell June 9, 1942i Stewart June 1, 1943 FOREIGN PATENTS Country Date Great Britain 1882 Great Britain Apr. 29, 1942 

